1. Field of the Invention
The present invention relates to blood pressure measuring devices of the type having an inflatable measuring sleeve, and in particular to blood pressure measuring devices which are equipped with a manually operable valve for the evacuation of the air from the measuring sleeve.
2. Description of the Prior Art
Blood pressure measuring devices of the type mentioned above are known from the prior art. One such device is described in the Offenlegungsschrift (German Printed Application) No. 2,118,295. This device features an air evacuation valve which is operable under finger pressure, using a thumb, for example, thereby making it possible to operate both manual pump and the evacuation valve with one hand only. This arrangement permits a convenient and sensitive control of the measuring device, so that the pressure inside the measuring sleeve can be lowered at the exact desired speed. With this instrument, it is no longer necessary to remove the pump and to place it aside. Rather, the pump itself will serve as a convenient handle for the compact valve housing mounted adjacent thereto.
The standard blood pressure test consists of measuring the systolic and diastolic pressures, the procedure being normally terminated as soon as the diastolic pressure has been ascertained. At this point, the measuring sleeve is still subjected to a considerable amount of pressure, which has to be lowered to zero, before the measuring sleeve is free of pressure and tension for removal from the limb on which the blood pressure test has been performed. This elimination of the residual air pressure from the measuring sleeve makes it necessary to maintain the spring-loaded plunger of the evacuation valve open, until such time as all the air is escaped from the measuring sleeve. However, because the pressure decrease follows an exponential function, the escape of air consumes a comparatively great amount of time, especially in the lower pressure range. With the intent of relieving the technician operating the blood pressure measuring device, it has been suggested, in a proposed solution which is not part of the prior art, to provide a locking means in conjunction with the actuating member of the valve plunger so as to maintain the latter in its open position, until the locking means is released. This solution does relieve the operating technician who, during this time, could for instance record the measured blood pressure values. However, the patient on which the blood pressure test has been performed must wait all this time with the measuring sleeve still attached, until the latter is completely free of pressure, before it can be removed from his limb.